Development of non‐invasive assessments on vitamin A status by using skin levels of carotenoids as biomarker – U.S. study (1022.8)

Abstract

BACKGROUND: Vitamin A Deficiency (VAD) is a major problem leading to blindness and childhood mortality. An estimated 250 million preschool children are VAD and a substantial proportion of pregnant women are also VAD. The methods used today for the diagnosis of VAD are anthropometry and biomedical tests, which are costly and time‐consuming. A rapid, convenient, and cost‐effective method is needed to monitor vitamin A status and catch the early stage of VAD. Carotenoids are called pro‐vitamin A that can be distributed into the top layer of the skin, therefore, the skin may become a mirror reflecting vitamin A status. Noninvasive reflectance spectroscopy has been reported to measure carotenoid levels in the skin; its advantages are quick, convenient and low cost; the measurement takes less than 60 seconds. OBJECTIVE: The noninvasive method can not be directly applied to assess the vitamin A plasma concentration. Therefore, the first stage of my research is to collect the data from human subjects to find out the corrections between skin levels of carotenoids and plasma concentrations of vitamin A. METHODS: The plasma samples of 68 subjects were kindly provided by a local sponsor's study; all subjects received the non‐invasive measurements on their skin levels of carotenoids by using a reflectance scanner. The plasma samples were extracted and assayed by validated extraction and HPLC methods. The regression analysis was conducted with both skin and plasma data. RESULTS: Subjects with low reflectance scores had low plasma vitamin A contents. The skin levels of carotenoids are well‐correlated with the β‐carotene plasma concentrations (r2=0.63), and also the skin levels of carotenoids has a good correlation with the vitamin A plasma concentrations (r2=0.56). CONCLUSION: The noninvasive reflectance spectroscopy method is feasible to measure the vitamin A concentration in the blood, and more data from developing countries are needed to support the correlations.